This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to evaluate the immunogenicity and therapeutic potential of an SIV vaccine consisting of priming with DNA adjuvanted with CD40L and Imiquimod, and boosting with modified vaccinia Ankara (MVA) in SIV-infected macaques. We constructed a DNA/SIV-CD40L VLP vaccine that co-expresses macaque CD40L along with SIV Gag-Pol and Env that forms virus-like particles (VLPs). The SIV-CD40L VLPs demonstrated a robust activation of DC as measured by expression of CD80 and CCR7, and secretion of TNF[unreadable] and IL-12. We then initiated a pilot macaque trial with four macaques to evaluate the therapeutic potential of CD40L adjuvanted DNA/MVA SIV vaccine. Macaques were infected with SIV mac251 and anti-retroviral therapy (ART) was initiated at 32 weeks to suppress viremia as well as for partial immune re-constitution. Macaques were primed with three doses for either adjuvanted or non adjuvanted DNA vaccine and were boosted with a single dose of recombinant modified vaccinia Ankara (MVA) expressing SIV components at 8 weeks interval. Macaques that received the adjuvanted vaccine also received Imiquimod during prime. Our preliminary analyses reveal that both adjuvanted and non adjuvanted vaccines elicit a robust T cell response following vaccination. At one week following the MVA boost, the functional quality (IFN-[unreadable]+IL-2+) of virus-specific CD8 T cells improved significantly compared to pre-ART time-points. Similarly, the magnitude and functional quality of virus-specific CD4 T cells also increased following vaccination. We are currently testing the adjuvanted DNA/MVA vaccine in a larger cohort of animals to evaluate the immunogenicity and protective efficacy of these vaccines in SIV infected macaques.